On Mon, May 04, 2009 at 05:25:13PM -0500, Serge E. Hallyn wrote:
> Quoting Oren Laadan (orenl@xxxxxxxxxxxxxxx):
> >
> > Serge E. Hallyn wrote:
> > > Quoting Matt Helsley (matthltc@xxxxxxxxxx):
> > >
> > > ...
> > >
> > >> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> > >> index a7acfe6..f16be9d 100644
> > >> --- a/fs/btrfs/super.c
> > >> +++ b/fs/btrfs/super.c
> > >> @@ -686,6 +686,7 @@ static const struct file_operations btrfs_ctl_fops = {
> > >> .unlocked_ioctl = btrfs_control_ioctl,
> > >> .compat_ioctl = btrfs_control_ioctl,
> > >> .owner = THIS_MODULE,
> > >> + .checkpoint = generic_file_checkpoint,
> > >> };
> > >
> > > Do we really want this one?
> >
> > We need to checkpoint the open file regardless of whether the underlying
> > filesystem has snapshot capabilities.
>
> But maybe we need to refuse a checkpoint if a task is talking to the
> underlying btrfs filesystem?
Good catch. The ctl file is a device node which, as best I can tell, is
empty. So the only obvious concern are the unlocked_ioctl()s. I expect
these ioctls() are "special" so generic_file_checkpoint() is probably
insufficient here.
v2 of the btrfs checkpoint op patch, which removes this hunk, is below.
A non-generic handler which blocks or prevents ioctl() during checkpoint would
seem to be required. Definitely a topic worthy of discussion on linux-fsdevel if
/when we add a .checkpoint op for this.
As best I can tell we don't have anything to handle the generic ioctl() case
either. Am I wrong?
Cheers,
-Matt Helsley
---
Add the checkpoint operation for btrfs files and directories.
Signed-off-by: Matt Helsley <matthltc@xxxxxxxxxx>
Cc: linux-fsdevel@xxxxxxxxxxxxxxx
---
fs/btrfs/file.c | 1 +
fs/btrfs/inode.c | 1 +
fs/btrfs/super.c | 1 +
3 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 482f8db..23d5c72 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1334,4 +1334,5 @@ struct file_operations btrfs_file_operations = {
#ifdef CONFIG_COMPAT
.compat_ioctl = btrfs_ioctl,
#endif
+ .checkpoint = generic_file_checkpoint,
};
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 65219f6..583d57e 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5158,6 +5158,7 @@ static struct file_operations btrfs_dir_file_operations = {
#endif
.release = btrfs_release_file,
.fsync = btrfs_sync_file,
+ .checkpoint = generic_file_checkpoint,
};
static struct extent_io_ops btrfs_extent_io_ops = {
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